The present invention relates to an optical disk player, and more particularly, to a motor rotation control device for an optical disk player.
FIG. 1 is a diagram of a conventional motor rotation control device 10. To rotate a stationary disk (not shown) at a normal speed, a system controller 100 outputs a forward acceleration signal to a motor rotation controller 102 causing a motor 104 to forwardly accelerate. When the disk is rotating at a normal speed, the system controller 100 supplies a normal driving signal to the motor rotation controller 102 causing the motor rotation controller 102 to continue rotation of the motor 104 so as to maintain a Constant Angular Velocity (CAV) or a Constant Linear Velocity (CLV) of the optical disk. If the motor 104 accelerates to an explosive (or overrun) state, the system controller 100 outputs a backward acceleration signal to the motor rotation controller causing the motor 104 to backwardly accelerate (i.e., decelerate) so as to reach a normal speed range. During operation, the motor 104 supplies motor rotation signals (including a period of rotation) to the system controller 100.
In summary, the motor rotation controller 102 causes the motor 104 to forwardly rotate in response to a forward acceleration signal, controls the motor 104 at a CLV/CAV in response to a normal driving signal, and causes the motor 104 to rotate backwards in response to a backward acceleration signal.
FIG. 2 is a flowchart of a conventional motor rotation control process. At step 200, the system controller 100 generates a forward acceleration signal to accelerate the motor 104 forwardly. At step 202, the system controller 100 checks the period of the rotation, using the motor rotation signal generated from the motor 104, and judges whether the number of rotations per unit of time of the motor 104 is greater than a number N corresponding to a forward acceleration limit speed. If the number of rotations is not greater than the number N, the process goes to step 204 and the system controller 100 continues to accelerate the motor 104 forwardly. If, in step 202, the number of rotations is greater than the number N, the process goes to step 206 and the system controller 100 checks whether the number of rotations per unit of time of the motor 104 is less than a number M corresponding to a backward acceleration limit speed.
If, in step 206, the number of rotations is less than the number M, the process goes to step 210 and the system controller 100 carries out normal CLV/CAV control of the motor 104. The process then returns to step 202. If, in step 206, the number of rotations is not less than the number M, the process goes to step 208 and the system controller 100 generates a backward acceleration signal to accelerate the motor 104 backwardly at step 208. The process then returns to step 202.
The system controller 100 must continually check the rotation period of the motor 104 so as to be able to set a forward acceleration speed and a backward acceleration speed for the motor 104. Hence, the system controller 100 must spend a lot of time checking the rotation speed of the motor 100. Unfortunately, in the conventional motor rotation control device, while controlling the motor 100 at a CLV/CAV, the system controller 100 does not know whether the motor 104 is rotating forwardly or backwardly. Therefore, it is difficult to prevent the motor 104 from rotating backwardly during focus drop, i.e., when the RF signal from the optical pickup contains only noise and no sync signal, and degrading the performance of an optical disk player.
The system controller 100 must continually check the rotation period of the motor 104 so as to be able to set a forward acceleration speed and a backward acceleration speed for the motor 104. Hence, the system controller 100 must spend a lot of time checking the rotation speed of the motor 100. Unfortunately, in the conventional motor rotation control device, while controlling the motor 100 at a CLV/CAV, the system controller 100 does not know whether the motor 104 is rotating forwardly or backwardly. Therefore, it is difficult to prevent the motor 104 from rotating backwardly during focus drop, i.e., when the RF signal from the optical pickup contains only noise and no sync signal, and degrading the performance of an optical disk player.